Giardia linked to IBS and chronic fatigue

Several infectious agents have been linked to CFS over the years. A study published on Sept. 12, 2011, in the journal Gut follows people living in Bergen, Norway, who become ill with giardiasis after a local water reservoir was contaminated with a common parasite, Giardia lamblia, in the fall of 2004.

During the giardiasis outbreak in the central part of Bergen, 2,500 people were treated with metronidazole, the standard therapy, representing about 1/10th of the city’s population. A team of researchers at University of Bergen followed 817 people who had laboratory-confirmed Giardia infection during this period, and 1,128 matched controls who were not affected. They report that three years after the outbreak, 46.1 percent of the people who were exposed to Giardia reported irritable bowel syndrome (IBS), compared to 14 percent in the control group. The same percentage – 46.1 percent – of the exposed group reported chronic fatigue, compared with 12 percent of controls.

The study was conducted by questionnaire, and medical evaluations were not performed. One of the study’s limitations is the inability to state how many of the individuals with fatigue and other symptoms would fully meet criteria for CFS, ME/CFS or ME under the various research and clinical definitions. In spite of this and other limitations, the finding of higher rates of persisting illness three years after known infection adds important information to the study of infectious triggers for CFS. The high rate of co-occurrence of IBS and chronic fatigue is another important finding that supports other studies in the medical literature.